Our proposed research uses a quasi-experimental design to estimate how treatment adherence, health outcomes, and labor supply respond to whether or not an individual's insurance is provided by their own employer. Because many women obtain health insurance through their spouse's employment, while many others obtain it through their own employment, the labor supply response of women to illness-and how that response depends on the source of the health insurance-provides a natural context for addressing our research questions. Thus, we chose employed, married women newly diagnosed with breast cancer and their spouses as subjects for an investigation into the relationship between ECHI, health, and labor supply. Our aims are: 1) To compare treatment and treatment adherence between women with employment- contingent health insurance and women with health insurance through their spouse. Suggestive evidence from our prior study indicated that women with ECHI may forego treatment (e.g., doses of radiation, courses of chemotherapy) to avoid interruptions in their ability to meet work demands. To formally investigate this, we propose to abstract treatment and treatment adherence data from medical records. We will then examine the relationship between treatment and treatment adherence based on source of health insurance. Treatment and treatment adherence may be indicative of long-term health outcomes such as cancer recurrence and mortality. 2) To compare changes in health status between women with employment- contingent health insurance and women with health insurance through their spouse. One of the most important aspects of our research is how policies such as ECHI ultimately affect health status. We will examine health status by obtaining women's responses to questionnaires (specifically, the SF-36 and the Functional Assessment of Cancer Therapy-Breast (FACT-B)) at 2, 6, and 12 months following diagnosis. 3) To compare labor supply responses to cancer between women with employment-contingent health insurance and women with health insurance through their spouse. We propose to collect data with which to compare the effects of breast cancer on the labor supply of employed married women 2, 6, and 12 months following diagnosis, relative to their labor supply at the time immediately preceding their diagnosis. 4) To examine the labor supply responses of spouses following their partner's breast cancer diagnosis. Conceivably, ECHI creates similar labor supply incentives for employed, healthy spouses of women with breast cancer as it does for women with the disease. Spouses with ECHI may maintain high labor supply and hence forego care giving activities so that they can preserve their ECHI. To our knowledge, this integral way of addressing the incentives and pitfalls of ECHI has not been previously examined.